Replacing fridge light with lower wattage LED bulb?

Submitted ⁨⁨4⁩ ⁨months⁩ ago⁩ by ⁨naught101@lemmy.world⁩ to ⁨askelectronics@discuss.tchncs.de⁩

I have a fridge with a burnt out incandescent ligth globe. The original was 20W. I tried to replace it with a 5W LED, and it lit up for about 1 second, and then went off. The bulb works fine in a lamp, so I’m guessing I blew something in the fridge electronics?

My electronics knowledge is pretty basic, but I figured that using a lower wattage globe couldn’t really hurt. It at least wouldn’t have blown a fuse, right? Is there something else it could have done? LED control circuit HF feeding back into the fridge power circuit badly or something?

The rest of the fridge is working fine.

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Gobo@lemmy.world ⁨4⁩ ⁨months⁩ ago
Different voltages? Ac vs DC? Get a multimeter and read what the socket in the refrigerator says.

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- naught101@lemmy.world ⁨4⁩ ⁨months⁩ ago
  It’s a standard e14 socket - I guess it’s AC? Not actually sure. I think the bulb should work for both though, 'cause it has a rectifier, I think?
  
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litchralee@sh.itjust.works ⁨4⁩ ⁨months⁩ ago
I’m taking a guess that perhaps the fridge makes similar assumptions that automobiles make for their lamps. Some cars that were designed when incandescent bulbs were the only option will use the characteristics resistance as an integral part of the circuit. For example, turn signals will often blink faster when either the front or left corner bulb is not working, and this happens to be useful as an indicator to the motorist that a bulb has gone bust.

For other lamps, such as the interior lamp, the car might do a “soft start” thing where upon opening the car door, the lamp ramps up slowly to full brightness. If an LED bulb is installed here, the issues are manifold: some LEDs don’t support dimming, but all incandescent bulbs do. And the circuit may require the exact resistance of an incandescent bulb to control the rate of ramping up to fill brightness. An LED bulb here may malfunction or damage the car circuitry.

Automobile light bulbs are almost always supplied with 12 volts, so an aftermarket LED replacement bulb is designed to also expect 12 volts, then internally convert down to the native voltage of the LEDs. However, in the non-trivial circuits described above, the voltage to the bulb is intentionally varying. But the converter in the LED still tries to produce the native LED voltage, and so draws more current to compensate. This non-linear behavior does not follow Ohm’s Law, whereas all incandescent bulbs do.

So my guess is that your fridge could possibly be expecting certain resistance values from the bulb but the LED you installed is not meeting those assumptions. This could be harmless, or maybe either the fridge or the LED bulb have been damaged. Best way to test would be installing a new, like-for-like OEM incandescent bulb and seeing if that will work in your fridge.

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- naught101@lemmy.world ⁨4⁩ ⁨months⁩ ago
  Interesting! Thanks! I’ll see if I can find a similar bulb and try it.
  
  I guess the fact that it worked for a second the first time and then stopped working entirely (but the bulb still works elsewhere) indicates I probably borked part of the fridge. Oh well, it wasn’t working for years anyway…
  
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BlackJerseyGiant@lemmy.world ⁨4⁩ ⁨months⁩ ago
A: You may have bought a bum bulb that burnt out after a moment

B: The switch on the door that turns the light on and off could be bad.

Screw in a different bulb. Test your new bulb in a different socket. Push the fridge door switch by hand and release it several times to see if it comes on, even momentarily. A bulb of lower wattage should not blow a fuse, unless said bulb was defective in such a way that it shorted the connection. Any HF switching shouldn’t be an issue either, as it would be just turning the power on and off rapidly, and should be “seen” by any electronics in circuit as average power draw.

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- naught101@lemmy.world ⁨4⁩ ⁨months⁩ ago
  I tried the bulb in a lamp and it’s fine, and other LEDs also failed.
  
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